As is known to those skilled in the art, tetragonal barium titanate is useful for the production of capacitors, dielectrics, piezoelectrics, positive temperature coefficient resistance devices(PTCR's), sensors, and the like.
For the aforementioned uses, tetragonal barium titanate should ideally be substantially pore free with substantially zero percent open porosity; a higher porosity barium titanate will generally have high energy losses and degradation of its desired properties. Furthermore, the barium titanate should also have a uniform microstructure with a controlled grain size on the order of from about 0.5 to 1.5 microns micron; barium titanate with a substantially different grain size will have substantially poorer properties.
To the best of applicant's knowledge, a process for the production of tetragonal barium titanate glass-ceramic film containing barium titanate as the only crystalline material with a uniform microstructure on an isostructural substrate has not been provided by the prior art.
It is an object of this invention to provide a process for the preparation of tetragonal barium titanate with a uniform microstructure of from about 0.5 to about 1.5 microns in a controllable, reproducible manner.